Portable memory devices, such as memory cards, are often used with consumer electronic devices, such as mobile phones and personal computers (PCs) to store and/or transport data. In addition to a storage medium, many portable memory devices contain circuitry, such as a microprocessor, that can transform addresses received from the host device to other addresses, thereby allowing the circuitry on the memory device to control where data is stored in the storage medium.
If a user loses his portable memory device, he faces the risk of others reading the data stored on the device, which may be highly undesirable since the data may be personal or confidential. One way to avoid such data leakage is to encrypt the data using an encryption algorithm such as Data Encryption Standard (DES) or triple-DES. For example, many mobile phone operating systems have a software encryption mechanism for encrypting data to be stored on a memory card inserted into the phone. One drawback to this approach is that the encrypted data can only be accessed from the mobile phone that encrypted the data and not by another host device, such as another mobile phone or a personal computer.
One approach for securing data on a portable storage device uses a storage medium including a secure user area and a microprocessor operable to allow access to the secure user area only when a user provides an appropriate password to the microprocessor.